1287665 has 8 divisors (see below), whose sum is σ = 1636200. Its totient is φ = 969472.

The previous prime is 1287661. The next prime is 1287683. The reversal of 1287665 is 5667821.

It can be written as a sum of positive squares in 4 ways, for example, as 379456 + 908209 = 616^2 + 953^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1287665 - 2² = 1287661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1287661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7490 + ... + 7659.

It is an arithmetic number, because the mean of its divisors is an integer number (204525).

2^1287665 is an apocalyptic number.

It is an amenable number.

1287665 is a deficient number, since it is larger than the sum of its proper divisors (348535).

1287665 is a wasteful number, since it uses less digits than its factorization.

1287665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15171.

The product of its digits is 20160, while the sum is 35.

The square root of 1287665 is about 1134.7532771488. The cubic root of 1287665 is about 108.7930027669.

The spelling of 1287665 in words is "one million, two hundred eighty-seven thousand, six hundred sixty-five".